This section is from the book "The Barnet Book Of Photography", by Herts Barnet. Also available from Amazon: The Barnet Book Of Photography.
A brand of P.O.P.s which are now coming into great favour are the so-called self-toning papers. In these papers the necessary amount of gold is apparently incorporated in the emulsion itself, and toning is effected by simple soaking in a solution that will reduce the gold to the desired colour. For the purple tone that seems to be the desire of all beginners the alum and sulphocyanide formula recommended by the makers is certainly the best, whilst for distinctly warm tones I have found the salt bath as already recommended for ordinary P.O.P. an excellent one. Self-toning papers should not have preliminary washing whichever bath is used. They are inserted dry (with all due precautions as regards bubbles), and after about five minutes' immersion, during which they are kept moving as in a toning bath, they should receive a good washing in the manner before indicated, when they are ready for fixing. By the use of this class of paper at least one bath is dispensed with, and there is a delightful certainty with which a large batch of prints can be brought to the same colour without a suspicion of double tones or even of unequal toning.
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